I've been looking for a good way to add thickness to my models for uploading. I'm also trying to teach my students how to hollow models. We have been using Zbrush with good results but there is no way to be precise with this.

I have been trying to use MESHLAB's Uniform Remeshing filter but not with much luck. The settings I am testing I have attached a screenshot of.

After using this function I do have a new layer called offset but there doesn't seem to be anything in it??? No faces or vertices I'm very confused could someone please help.

The trick is to create and inner and outer offset shells, then remove the outer shell.
Check 'Absolute Distance' and use a positive abs offset value to create the both inner & outer offset shells.
Used the 'select connected components in a region' tool (underlined in red in the image) and just touch the outer shell with the lasso box.
Hit delete and turn off visability for the original mesh to see the inner offset shell.

If you know the dimensions of the model, you can specify the offset as the ABS value, otherwise you're stuck to calculating the offset needed. From the numbers for 'Precision' it looks like the model has largest length as 6.39 units, enter the 'world units' value for the wall thickness you need in the offset abs box.

The reccommended settings are those that are right for the size of the model and the material that the model is intended to be printed in.